The present invention relates to the preparation of collagen-coated foodstuffs, especially sausages.
There are two approaches to making sausages. The first is to take natural or artificial sausage casing and stuff it with sausage meat. In recent times, it has become known to co-extrude a strand of sausage material which has an inner core of meat emulsion having an outer surface material that can be coagulated to provide an encasement for the strand. The outer surface material may consist of a gel with a collagen protein.
A typical sausage coextrusion process is described in U.S. Pat. No. 622,353 Bradly, et al. In practice this process includes the steps of co-extruding a substantially uniform layer of collagen gel around an edible product, whereby the collagen is coagulated by passing the extruded sausage strand through a brine bath, subsequently crimp/cutting the strand into individual sausage links and successively air drying these links.
The linking is done by a so-called crimping-wheel. For instance described in U.S. Pat. No. 5,104,349 to Van Der Dungen, et al., a crimping wheel normally has a horizontal axis, and has a plurality of crimping units mounted on its circumference. These crimping units are spaced apart to form the required sausage length. The crimping units consist of two oppositely oriented V-shaped members to form a scissors. Said members are brought together through a cam on the wheel, to first constrict the sausage strand and subsequently separate the links.
Usually the sausage rope is fed to the crimping-wheel at the wheel's top, to have the sausage links drop from the wheel lower end. In between the crimping units the sausage strand is usually supported to prevent the breaking of the casing which at this point of process is still relatively weak. The speed of the linker is equal to that of the coextrusion unit so that no tension is exerted on the rope.
In more recent times developments have led to coextrusion processes which give a stronger casing, making it practically possible to twist-link the sausage strand and/or hang it. See for instance our International Patent application Wo 94/11474 to Kobussen, et al.
In International Patent application WO 94/23584 to Hanlon, et al. a linking wheel is provided which twist-links a coextruded sausage strand and subsequently hangs the linked sausages onto a conveyor. This disclosure describes similar v-shaped crimping units on a rotating wheel. Between the crimping units roller means are applied to twist the sausage rope around the longitudinal axis.
All previously known methods of linking a co-extruded sausage strand have not dealt sufficiently with the irregular shaped sausage as a result of these processes.
Regardless of which linking method is used, sausage meat is pushed aside from the linking points which results in a so-called dumbbell shape of the sausage, which is an expansion of sausage diameter at sausage ends. Particularly for co-extrusion, this is a problem since the casing produced is more flexible than natural or prefabricated casings, and can therefore not give the necessary casing strength to withstand the dumbelling effect.
Other irregularities of sausage shape can also be contributed to the fact that the extruded sausage emulsion defines the shape of the end-product as the collagen is coagulating around it. As opposed to preformed casings, where the meat is stuffed into a given confinement which sets the sausage shape, these irregularities are more predominant with course ground meat emulsions, as compared to relatively fluid frankfurter-type meat doughs.
Irregularities are particularly problematic for fresh sausage products. Cooked type products are often further processed, and this further processing can be used to minimize unwanted irregular product shape. Fresh sausage, after coextruding, coagulating and linking, are often quickly fried or baked which increases the irregularities.
In addition to the lower value of irregular shaped sausages, they tend to split or break during cooking. Dumbelling particularly creates excessive expansion of meat from the sausage ends, because during cooking the casing shrinks while the meat batter expands. This is particularly so with fresh sausage, wherein breakage of the casing often occurs.
It is therefore a principal object of the present invention to provide a method for manufacturing co-extruded food strands with an edible casing in which the previous problems and disadvantages of the known co-extrusion methods do not occur.
It is a further object of the present invention to provide a novel method for reducing unwanted irregular shape of a co-extruded food product.
It is still a further object of the present invention to provide a novel method for reducing unwanted dumbelling of a co-extruded food product.
It is still a further object of the present invention to provide a novel method for substantially reducing breakage of co-extruded sausage links during cooking.
An additional object of the present invention is to create by co-extrusion a substantially uniform layer of a collagen containing gel around an elongated strand of foodstuff and coagulating the foodstuff by contacting it with a salt containing brine, and stretching the strand before linking it.
These and other objects will become clear from the following description of the present invention.